Suppose there are four dominant manufacturers of toilet tissue. the largest of these manufacturers announces that it will raise its prices by 15 percent due to higher paper costs. within three days, the other three dominant toilet tissue manufacturers announce similar price hikes. the decision among the four companies to raise prices would a. be evidence of explicit collusion because they are all large companies. b. not be explicit collusion unless there was clear evidence of an agreement among the manufacturers. c. not be explicit collusion unless there was a written agreement among the manufacturers. d. be evidence of explicit collusion since they all acted similarly.